That's a good question. But we have to remember what happened with Google Glass. Glassholes were inconsiderate google glass users that refused to take google

That's a good question. But we have to remember what happened with Google Glass. Glassholes were inconsiderate google glass users that refused to take google glass off when interacting with people. Duplex will end up like Google Glass for a similar reason -- people will force other people to interact with robots. I think if I'm a human on the phone more than a few minutes a day, I might take exception to that. Especially if more than a few calls come in that way and there are enough bugs in the system to make it annoying. One particular countermeasure will be to require a credit card number (or some other personal information) for cancellation... which I'm not sure Google Duplex would be willing to hand out over the phone.